The invention related to an extrusion device for the production of plastic hollow profiles filled with foam, whose cross-section consists of at least one hollow profile section, with the following individual parts:                one extruder for the processing and supply of a plastic melt;        one profile tool connected to the extruder at one melt inlet opening carrying the melt and including a profile nozzle with at least one hollow profile nozzle section;        at least one foam lance, which, at least partly, is arranged inside a melt radial channel leading to the profile nozzle and coaxially to a discharge direction of the plastic hollow profile coming out of the profile nozzle.        
A method and a device for the continuous extrusion of endless profiles with a coating of thermo-plastic synthetic material and a foam core is know from DE-OS 1 959 454. In a profile tool of an extruder for the production of a coated profile with a hollow space, a mixture carrying pipe is arranged, through which a reaction mixture can be injected in the hollow space in order to form a foam core. The plastic profile is subsequently sent to a cooling and calibrating system. The mixture supplying pipe reaches into the hollow space of the calibrating device. The nozzle of the mixture supplying pipe lies in an area above the profile wall, in which the temperature of the coated profile is reduced to at least 100° C., in particular from 20° up to 50° C. The length of the mixture supplying pipe can be adjusted in order to set the axial position of the nozzle. However, a disadvantage in this is that the reaction mixture injected through the nozzle can flow back to the hot area of the coated profile. The hereby proposed encircling of the nozzle with a seal ring sealing the ring space between the mixture supplying pipe and the coated profile, does not only imply additional costs but is also troublesome, seeing that the accumulating foam front lies directly in front of the injection nozzle. To glue the seal ring, the entire profile tool would have to be taken apart. The firmly glued mixture supplying pipe can only be removed only if the coated profile pipe is destroyed. The known method and the known device cannot ensure a trouble-free and unsupervised operation.